This daemon feeds data from a random number generator to the kernel's
random number entropy pool, after first checking the data to ensure that
it is properly random.
The -f or --foreground options can be used to tell
rngd to avoid forking on startup. This is typically used for
debugging. The -f or --foreground options, which fork and put
rngd into the background automatically, are the default.
The -r or --rng-device options can be used to select an
alternate source of input, besides the default /dev/hwrandom.
The -o or --random-device options can be used to select
an alternate entropy output device, besides the default /dev/random.
Note that this device must support the Linux kernel /dev/random
ioctl API.
FIXME: document random-step and timeout
OPTIONS
-b, --background
Become a daemon (default)
-f, --foreground
Do not fork and become a daemon
-o file, --random-device=file
Kernel device used for random number output
(default: /dev/random)
-r file, --rng-device=file
Kernel device used for random number input
(default: /dev/hwrandom)
-s nnn, --random-step=nnn
Number of bytes written to random-device at a time (default: 64)
-W n, --fill-watermark=nnn
Once we start doing it, feed entropy to random-device until at least
fill-watermark bits of entropy are available in its entropy pool (default: 2048).
Setting this too high will cause rngd to dominate the contents of the
entropy pool. Low values will hurt system performance during entropy
starves. Do not set fill-watermark above the size of the
entropy pool (usually 4096 bits).
-t nnn, --timeout=nnn
Interval written to random-device when the entropy pool is full, in seconds, or 0 to disable (default: 60)
